112 research outputs found
Active vibration isolation performance of the bistable nonlinear electromagnetic actuator with the elastic boundary
No full textThis paper thoroughly investigates the broadband active vibration isolation of a bistable nonlinear electromagnetic actuator with an elastic boundary (simply named EB-bistable actuator). A new feedback control law is proposed to control the actuator's input current, to significantly attenuate the broadband vibration transmissibility from the base excitation to the actuator mover (supporting the payload). The control law comprises the polynomial function of the mover's absolute velocity. The mathematical models of the EB-bistable actuator and its application for vibration isolation are derived and experimentally validated. Then, based on the verified model, the paper comprehensively investigates the EB-bistable actuator with the proposed control law, which validates the broadband active vibration isolation performance for different system parameters. The input-to-state stability (ISS) of the control law for any non-negative control weights is proved, and thus it is a model-free control method. Results of one investigated case show that the maximum vibration transmissibility can be attenuated by over 90%. The lower bound of the effective vibration isolation bandwidth (where the vibration transmissibility is smaller than 0 dB) is reduced by 19.69%, i.e. the bandwidth is significantly broadened. Moreover, the study proves the effectiveness of the active vibration isolation for the structural variation and initial condition change. Finally, the paper thoroughly discusses the influence of the control law parameters on the active vibration isolation performance. The parametric studies develop useful guidelines for the active vibration isolation of the EB-bistable actuator.</p
sj-docx-1-pss-10.1177_09567976211056620 – Supplemental material for Identifying Long- and Short-Term Processes in Perceptual Learning
No full textSupplemental material, sj-docx-1-pss-10.1177_09567976211056620 for Identifying Long- and Short-Term Processes in Perceptual Learning by Jia Yang, Fang-Fang Yan, Lijun Chen, Shuhan Fan, Yifan Wu, Lei Jiang, Jie Xi, Junlei Zhao, Yudong Zhang, Zhong-Lin Lu and Chang-Bing Huang in Psychological Science</p
Machine learning based prediction of piezoelectric energy harvesting from wake galloping
No full textWake galloping is a phenomenon of aerodynamic instability and has vast potential inenergy harvesting. This paper investigates the vibration response of wake galloping piezo-electric energy harvesters (WGPEHs) in different configurations. In the proposed system, astationary obstacle is placed upstream, and a cuboid bluff body mounted on a cantileverbeam with piezoelectric sheets attached to it, is placed downstream. Three different typesof WGPEHs were tested with different cross-section S of the upstream obstacles, namelysquare, triangular, and circular. At the same time, the tests were conducted by changing theequivalent diameter ratio g ¼ 1 2:5 of the upstream and downstream objects, the dimen-sionless distance between two objects’ centers L ¼ L=D ¼ 2 8, and the velocity spanU ¼ 2:93 14:54. The results reveal that S , g, L and U have significant effect on thevibration response of WGPEHs. Then, considering these four parameters as input features,this study has trained machine learning (ML) models to predict the root mean square val-ues of the voltage (V rms ) and the maximum displacement (ymax), respectively. The perfor-mance of three different ML algorithms including decision tree regressor (DTR), randomforest (RF), and gradient boosting regression trees (GBRT) on predicting V rms and ymax werecompared. Among them, the GBRT model performed optimally in predicting the V rms andymax . The GBRT model provides accurate predictions to V rms and ymax within the test range of S , g, L and U.<br/
Mechanical Determinants of Superior Horizontal Deceleration Performance in Multidirectional Sportspersons.
No full textLi, W, Lin, J, Dos'Santos, T, and Turner, A. Mechanical determinants of superior horizontal deceleration performance in multidirectional sportspersons. J Strength Cond Res XX(X): 000-000, 2025-This study aimed to (a) examine the mechanical determinants of superior horizontal deceleration and (b) compare ground reaction force (GRF) characteristics of the first and second braking foot contacts during horizontal deceleration between higher and lower deceleration performers. Forty-two trained male student-athletes from multidirectional team sports performed 3 maximal deceleration trials after a 15-m sprint, with GRF data over the first 2 braking steps collected using force plates. Horizontal velocity was collected using a radar gun, and p < 0.05 was considered statistically significant. Greater mean and peak deceleration were statistically significantly correlated with greater mean horizontal GRF ratio at both braking foot contacts (ρ = 0.31-0.49, p < 0.05). Comparing lower mean and peak deceleration performers, greater performers displayed statistically significantly greater mean horizontal GRF ratios at both braking steps (effects size [ES] = 3.53-5.00, p < 0.05) and lower approach momentum (ES = 0.62 and 0.66). Compared with lower approach momentum performers, greater performers displayed statistically significantly greater mean and peak deceleration scores (ES = 0.70 and 0.66, p < 0.05). Practitioners should aim to maximize horizontal GRF production and orientate force more horizontally for more effective deceleration. However, faster approach velocities, especially when accompanied with greater body mass (and thus momentum), will likely see a reduction in deceleration performance on account of higher braking demands. This is likely an unavoidable paradox, and thus, deceleration performance must always be presented considering approach velocity and momentum
Effects of school-based neuromuscular training on fundamental movement skills and physical fitness in children: a systematic review
No full textOBJECTIVES: The primary purpose of this review was to clarify the effects of school-based integrated neuromuscular training (INT) on fundamental movement skills and physical fitness in children. The secondary purpose was to examine whether school-based INT intervention is superior to physical education (PE) intervention in enhancing motor skills and fitness. METHODS: A systematic literature search was performed in four electronic databases: PubMed, Web of Science, MEDLINE (EBSCOhost), and Cochrane Central Register of Controlled Trials. The last search was performed on December 21, 2021, and was limited to the English language, human species, and peer reviewed journals. Randomized controlled trials and cluster randomized controlled trials that examine the effects of school-based INT on motor skills and/or fitness in healthy children who were aged up to 14 years old were included. Moreover, studies included in this study should compare school-based INT-induced adaptions with those generated by PE interventions. Studies that involve athletic children and additional exercise training were excluded. The Physiotherapy Evidence Database (PEDro) scale was used to assess the quality of the study. RESULTS: Of 1,026 studies identified, seven original trials that meet the inclusion criteria were included in this review. Based on the PEDro scale, the PEDro score of seven studies was between six and eight points with a mean score of 5.29. Among the seven studies included in this study, four studies assessed physical fitness including muscular fitness (n = 4), speed (n = 3), endurance (n = 2), and flexibility (n = 2). Three studies examined the effects of INT on postural control and three studies explored its effects on motor skills. Concerning movement competence, significant and greater improvements in postural control and fundamental motor skills were observed following school-based INT interventions compared to PE intervention in two and three studies, respectively. Regarding physical fitness, neuromuscular training significantly increased muscular fitness, speed, endurance, flexibility in three, two, one, and one studies, respectively. However, only greater improvements in muscle fitness were observed in school-based INT group compared to PE group. The main limitations of this review were the lack of descriptions of training intensity and volume and the low methodological quality of the included studies. CONCLUSION: This review provides evidence that school-based neuromuscular training programs are superior to PE lessons in improving postural control, fundamental motor skills and muscular strength. Therefore, INT could be incorporated into traditional physical education classes in school. Trial registration number: CRD42022297349
Relationships between Functional Movement Quality and Sprint and Jump Performance in Female Youth Soccer Athletes of Team China
No full textThis study aimed to determine the optimal functional movement screen (FMS) cut score for assessing the risk of sport injury, and to investigate the correlations between functional movement quality and sprint and jump performance. Twenty-four (N = 24) athletes performed all tests in one day at 10–30 min intervals, and the FMS test was performed first, without a warm-up session. After a standard warm-up, athletes then completed the Y-balance Test (YBT), sprint, counter-movement jump (CMJ), and standing long jump (SLJ), in turn. For each test, the best of three attempts was recorded for further analysis. A receiver operating characteristic (ROC) curve and area-under-the-curve (AUC) were used to determine the optimal FMS cut score for assessing the risk of sport injuries, and Spearman’s rank correlation analysis was used to quantify associations between functional movement scores and athletic performance. The average FMS score was 16.2 and the optimal FMS cut score for assessing the risk of sport injuries was 14.5. There were moderate relationships between total FMS score and 10–20 m sprint time (r = −0.46, p < 0.05), between In-line Lunge and 0–20 m sprint time (r = −0.47, p < 0.05), between Shoulder Mobility and 0–10 m sprint time (r = −0.48, p < 0.05), and between Trunk-stability Push-up and 10–20 m sprint time (r = −0.47, p < 0.05). Moreover, Hurdle Step score was largely correlated with 0–10 m time (r = −0.51, p < 0.05). For Y-balance, moderate correlations were observed between CMJ height and anterior asymmetry score (r = −0.47, p < 0.05) and posteromedial asymmetry score (r = −0.44, p < 0.05). However, there were no significant associations between YBT performance (asymmetric in three directions and composite score) and sprint performance (p > 0.05). Taken together, the results indicate that a FMS score of 14 is not a gold standard for assessing the risk of injury in all populations; we recommend that the FMS cut score of 14.5 should be the optimal score for assessing risk of injury in young female elite soccer players. Moreover, the FMS and YBT were introduced to assess the quality of functional movements, and they cannot be used to assess sprint and jump performance. Practitioners can use components of the FMS that have similar characteristics to specific sports to assess athletic performance
Woodland Cover Change Assessment Using Decision Trees, Support Vector Machines and Artificial Neural Networks Classification Algorithms
No full textEngaging in Drama Criticism: Zang Maoxun and His Four New Musical Texts from the Jade Tea Hall
No full textabstract: This dissertation focuses on the corpus of Zang Maoxun’s literary creations in The Collection from the Fubao Hall and investigates his involvement in the cultural activities of the Jinling Poetry Society. Unearthing how Zang and this Society, as self and community, played an instrumental role in creating and sustaining a network of dramatists and drama critics in the Jiangnan region, a careful review of his poems and prose shows the extent to which text preparation, commentary, and printing were at the center of his communications with his social circle. Moreover, this dissertation unpacks Zang’s contribution to the promotion of dramatic texts through a thorough examination of his ardent editorial work in revising Tang Xianzu’s The Four Dream Plays from the Jade Tea Hall, the epitome of the southern musical drama. By using Zang’s 1618 Diaochong guan edition of his adaptations as a focal point, this dissertation compares it with three late Ming editions of Tang’s plays printed in the dual colors of red-and-black ink. In light of their innovative editorial designs, and the varying evaluations formed in their pages about Zang’s editorial work, this dissertation reveals the importance of Zang’s adaptations in the history of The Four Dream Plays’ textual transmission, as well as the interplay between the tradition of drama criticism and the new technology of multicolor printing and consequent innovation in editorial principles.Dissertation/ThesisDoctoral Dissertation East Asian Languages and Civilizations 201
The state-of-the-art review on energy harvesting from flow-induced vibrations
No full textIn this paper, the currently popular flow-induced vibrations energy harvesting technologies are reviewed, including numerical and experimental endeavors, and some existing or proposed energy capture concepts and devices are discussed. The energy harvesting mechanism and current research progress of four types of flow-induced vibrations, such as vortex-induced vibrations, galloping, flutter and buffeting, are introduced. To enhance the performance of the harvesters and broaden the operating range, the researchers have proposed various mechanical designs, methods of the structures’ surfaces optimization and concepts with incorporated magnets for multistability. The paper summarizes the works led to the current wind energy and hydro energy harvesters based on the principle of flow-induced vibrations, including bladeless generator Vortex Bladeless, University of Michigan vortex-induced vibrations aquatic clean energy, Australian BPS company's airfoil tidal energy capture device bioSTREAM, and others. This shows the gradual progress and maturity of the flow-induced vibrations energy harvesters. The article concludes with a discussion on the current problems in the area of the flow-induced vibration energy capture and the challenges faced
Is There a Performance‐Injury Conflict Between Maximum Horizontal Deceleration and Surrogates of Noncontact Anterior Cruciate Ligament Injury?
No full textThis study aimed to examine the biomechanical determinants of horizontal deceleration and their correlations with noncontact ACL injury surrogates (e.g., knee joint moments). Thirty‐two male team‐sport players (Age: 21.85 ± 0.33 years; Height: 1.80 ± 0.11 m; Mass: 71.28 ± 1.39 kg) performed horizontal deceleration following 15 m sprints. Lower limb kinetics and kinematics of the first braking step were collected using 3D motion and force plates, and deceleration was assessed using radar gun. The Pearson correlation was used to determine correlations between selected variables and p ≤ 0.05 was considered statistically significant. Greater peak and mean horizontal deceleration were significantly correlated (p ≤ 0.05) with greater mean horizontal braking GRF (r = 0.52 and 0.41) and greater mean horizontal braking GRF ratio (r = 0.43 and 0.48). Greater knee joint loading (knee flexion moment, knee abduction moment, and knee internal rotation moment) were significantly correlated (p ≤ 0.05) with greater peak and mean vertical braking GRF (r = 0.30–0.41) and greater peak resultant braking GRF (r = 0.33–0.48). There were nonsignificant correlations between mean and peak deceleration and knee joint loading variables (p > 0.05). Therefore, deceleration strategies that emphasize greater horizontal and posteriorly orientated forces during the first contact of deceleration appear effective for facilitating more effective deceleration, without concomitant increases in the loading of noncontact ACL injury surrogates
- …
